1. Field of the Invention
The present invention relates generally to the field of artificial limbs. More particularly, the present invention relates to leg prostheses including energy absorption and storage mechanisms.
2. General Background
Various types of leg prostheses are known which are designed to provide a support structure upon which the wearer can place his or her weight while standing or during the gait and/or stride associated with walking. The goal being to simulate the function and performance of the human leg. To accomplish this, leg prostheses generally include a mechanism for attachment to the limb of the wearer and an extension (pylon) mechanism either including or in combination with a foot prosthesis. The length and composition of the leg prosthesis being dependent upon the requirement of the wearer. The result being a rigid support mechanism simulating the structure of the human leg extending from the wearer's limb to the ground to provide the necessary support and balance for human activity. Such mechanisms are known in the industry as static leg prostheses.
Problems associated with static leg prostheses have been found with regard to their ability to simulate fluid stride cadence during walking, running, or other physical activities such as sports, exercise or labor. As a result, the ability of prosthesis wearers to participate in such activities has been historically limited.
In order for a static leg prosthesis to properly support a wearer, the prosthesis must be the same length as the other leg (or second prosthesis) of the wearer. However, while walking or running, the wearer must flex his or her hips to allow the prosthesis to swing forward for the next step without contacting the ground and also allow enough time for the prosthesis to swing forward in order to properly support the wearer on the next step.
An additional problem exists in that the gait/stride cadence of the wearer must be modified because of the inability of the static prosthesis to propel the body forward. This forward/upward force is a physiokinetic result of the flex of the calf muscles, ankle and foot of the human leg. Accordingly, a need exists for a pylon assembly for a leg prosthesis which reciprocates thereby varying the length of the prosthesis and provides alternating energy storage and release capability.
Another important limitation of leg prostheses presently available is the inability to provide for rotation of the wearer's limb with respect to the prosthetic foot along the length of the prosthesis pylon. Such rotation is a natural physiological characteristic of the human hip, thigh, knee and ankle necessary to successfully or competitively perform certain physical motions. In order to accurately simulate the human leg, a prosthesis must provide for this rotation.
In certain activities, such as a golf swing, It is necessary to provide rotation of the wearer's limb with respect to a fixed prosthetic foot. However, although rotation is necessary for many activities, unrestricted (free) rotation reduces the stability and/or controllability of the leg for other activities. A need, therefore also exists for a prosthesis pylon with provides rotation within preset limits which may be varied as required by the wearer or the activity.